Shoulder
Luxation
Medial
Lateral
Osteochondritis dissecans - Caudal aspect of humeral head
Biceps tenosynovitis
Medial glenohumeral instability
Supraspinatus tendinopathy
Contracture of infraspinatus muscle
Fracture
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Luxation
Medial - much more common
Lateral
Signalment
Breeds – Toy and miniature breeds may have congenital shoulder luxation. Any breed may have a shoulder luxation due to trauma, especially larger dogs
Gender – No known gender predilection
Age – Congential shoulder luxation generally first noted from 3 to 9 months of age. Traumatic causes can occur at any age.
Etiology - Congenital causes may be due to abnormal flattening of the head of the humerus and abnormal shape of the glenoid. Occassionally there may be bilateral congenital shoulder luxations. Trauma may result in traumatic shoulder luxation. Patients should also be evaluated for thoracic trauma and other fractures of the forelimb.
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History
Moderate to severe lameness, may hold forelimb in a flexed nonweight-bearing position
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Clinical Findings
Moderate to severe lameness, atrophy of the forelimb muscles, hypertrophy of the pelvic limb muscles, abnormal position of the greater tubercle of the humerus relative to the acromial process of the scapula, with the acromial process located more lateral in cases of medial shoulder luxation.
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Diagnostics
Generally diagnosis suspected on orthopedic exam and confirmed with radiographs of the shoulder joint.
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Lateral view of a medial shoulder luxation. Note the head of the humerus is located proximal to the glenoid.
Cranial caudal view of a medial shoulder luxation. Note the head of the humerus is located medial to the glenoid.
Treatment Options
Some congenital cases have been treated conservatively. These cases generally stabilize by one year of age and dogs are relatively comfortable. However, lameness and atrophy persist. Other options include excision arthroplasty of the humeral head followed by physical rehabilitation, and arthrodesis. Arthrodesis is generally a last option.
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For traumatic shoulder luxation, when the patient is stable, general anesthesia is administered to allow painfree manipulation during reduction. The leg is hung using an IV pole or other means for 10 minutes to fatigue muscles. Distraction is applied, and if the luxation is medial, the humeral head is pushed laterally while distracting. Shoulder luxations are usually relatively easy to reduce. If the luxation is medial, a Velpeau sling is applied. If the luxationis lateral, a Spica splint is applied. Coaptation is applied for 2 weeks, then restricted activity for 4-6 more weeks.
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Velpeau sling
Alternatively, surgical repair of shoulder luxation may be performed. Transposition of the biceps tendon has been used. With this technique, the biceps tendon is transposed to a more medial position so that tension applied by the transposed biceps tendon helps to keep the shoulder from re-luxating. Primary repair of the damaged tissues is difficult because they are often severely damaged and do not hold suture very well. Prosthetic capsule repair with screws, washers and suture have been used.
More recently, a tightrope procedure has been used. With this technique, tunnels are drilled in the proximal humerus and the neck of the scapula. Strong suture is passed through the tunnels, and the suture is anchored on both ends to maintain tension and prevent re-luxation.
Repair of medial shoulder luxation with a tightrope procedure. Note the toggle anchor on the lateral scapular neck and the button on the lateral proximal humerus. Suture is tightened to maintain reduction.
Osteochondritis Dissecans
Signalment
Breeds – Large and giant breed dogs
Gender – Males are predisposed, but females also affected
Age – Generally noted from 4 to 9 months of age
Etiology - Abnormal endochondral ossification of the deep layers of articular cartilage results in focal areas of thickened cartilage that are prone to injury. In the absence of excessive stress, the lesion may heal. However, further stress on the cartilage may result in a cartilage flap. This condition is termed osteochondritis dissecans (OCD).
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History
Mild to moderate lameness, decreased activity
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Clinical Findings
Mild to moderate lameness, atrophy of the forelimb muscles, pain may be elicited with extension of the shoulder
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Diagnostics
Generally diagnosis suspected on orthopedic exam and confirmed with a lateral radiograph of the shoulder joint.
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OCD lesion. Note the flattened area on the caudal head of the humerus. The flap has undergone mineralization and is visible, but they often are not visib because cartilage is radiolucent.
Treatment Options
Removal of cartilage flap with an arthrotomy or arthroscopy, curettage of subchondral bone, change diet to a large breed growth diet, nonsterodal anti-inflammatory medication, rehabilitation
Biceps tenosynovitis
Signalment
Breeds – Generally large breed dogs
Gender – No gender predilection
Age – Commonly seen in middle- to older-aged dogs
Etiology – Degenerative process of the tendon and tendon sheath of the biceps brachii muscle.
History
Variable weight bearing lameness, often have initial lameness, improves, then worsens again
Clinical Findings
Variable weight bearing lameness. Flexion of the shoulder joint with simultaneous extension of the elbow joint increases the tension on the biceps tendon as it crosses over the bicipital groove, resulting in discomfort. In addition, there may be pain on direct palpation of the bicipital groove of the proximomedial aspect of the humerus.
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Test for biceps tenosynovitis by simultaneously flexing the shoulder joint and extending the elbow to increase stress on the biceps tendon. Normally the antebrachium should be parallel with the spine. Pain prior to that suggests biceps tendon pain.
Diagnostics
Radiographs may demonstrate mineralization of the bicipital tendon, enthesiophytes in the intertubercular groove, or other degenerative changes. Diagnosis can be difficult and is sometimes made by diagnostic ultrasound, magnetic resonance imaging, or observation during arthroscopy.
Normal biceps tendon
Partially torn biceps tendon
Treatment Options
Conservative management involves rest and injection of biological therapies, such as platelet rich plasma or stem cells, into the shoulder joint which communicates with the biceps tendon sheath. Corticosteroid injections have also been performed. Pulsed mode therapeutic ultrasound and therapeutic laser may also be used over the tendon. Oral non-steroidal anti-inflammatory drugs (NSAIDs) and cryotherapy are also be prescribed.
In cases that fail to respond to conservative measures, surgical release of the biceps tendon alone, or surgical release and re-attachment to the proximal humerus are performed.
Medial glenohumeral instability
Signalment
Breeds – Any breed is susceptible
Gender – No gender predilection
Age – Any age, more common in middle-aged dogs
Etiology – Increasingly recognized as a source of forelimb lameness, perhaps as a result of increasing advent of sporting activities which require rapid turning and jumping, and also from shifting weight to the forelimbs as a result of pelvic limb conditions. Damage of the medial glenohumeral ligament, subscapularis tendon, and joint capsule may occur.
History
Dogs may have mild to severe lameness, which may be acute with sudden trauma. Alternatively, dogs may demonstrate lameness that varies in severity as the condition becomes more common. Working and sporting dogs that place torsional stress on the shoulder joint may be predisposed, as well as dogs with bilateral pelvic limb conditions that result in shifting weight bearing forces to the forelimbs.
Clinical Findings
Lameness and excessive abduction of the shoulder joint while the shoulder is fully extended. Pain is also present at the end of abduction.
Diagnostics
MRI may reveal damage to the medial glenohumeral ligament or subscapularis tendon, but frequently the severity of injury is underestimated. Although ultrasound has been used, many artifacts as a result of difficulty in placing the probe in a perpendicular fashion makes interpretation suspect. Arthroscopic evaluation is the gold standard of assessing the type and severity of injury.
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Testing for medial shoulder instability
It is important to fully extend the shoulder to tighten the medial glenuhumeral structures. Stabilize the scapula, and then abduct the humerus. There should be less than 30 degrees of abduction, and no pain at the end of abduction.
Treatment Options
Mild cases may be treated with extracorporeal shockwave treatment, hobbles to prevent abduction, and rest for 4-8 weeks. In unresponsive or severe cases, the shoulder may be stabilized with a tightrope procedure or tissue anchors and suture, followed by hobbles placed for 4 weeks. Rehabilitation begins slowly, with leash walk and gentle range of motion exercises. Strengthening exercises of the supporting muscles of the shoulder may be initiated 6-8 weeks after surgery.
Normal subscapularis and Medial Glenohumeral Ligament cranial portion
Longitudinal tear of Medial Glenohumeral Ligament cranial portion
Damaged subscapularis muscle with synovitis. Note normal cranial arm of medial glenohumeral ligament at the top of the image.
Lateral radiogaph following tightrope stabilization of medial shoulder instability
Cranial caudal view following tightrope stabilization of medial shoulder instability
Supraspinatus tendinopathy
Signalment
Breeds – Medium and large breed dogs
Gender – No gender predilection
Age – Generally middle aged to older
Etiology – Often associated with working or sporting activities with torsional stresses on the shoulder joint that result in damage to the tendon.
History
Mild to moderate lameness, sometimes waxing and waning in nature. Sometimes dogs have a sudden onset of lameness.
Clinical Findings
Mild to moderate lameness. Pain at the insertion of the supraspinatus tendon on the greater tubercle of the humerus, especially when the shoulder is flexed and internally rotated to increase tensile forces on the tendon.
Diagnostics
Ultrasound is the generally the most beneficial diagnostic test. Radiographs, especially a skyline view of the tendon insertion, may show mineralization of the tendon.
Treatment Options
Medical treatment includes rest, NSAIDs, cryotherapy, and passive range of motion (PROM) exercises. Therapeutic ultrasound has been used in humans to treat calcification, and may be beneficial for dogs. Biologic therapies including platelet rich plasma or stem cells injected into diseased tissue is often useful. Surgical excision of the mineralized tissue may be performed in some cases. Tendon reattachment with tissue anchors may be performed in severe cases. After surgery, a carpal flexion bandage may be applied for 2 weeks to prevent weight bearing. Activity is limited for an additional 2 to 3 weeks.
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Contracture of infraspinatus muscle
Signalment
Breeds – Generally occurs in sporting and working dogs
Gender – No gender predilection
Age – Mature dogs
Etiology – Exact etiology is unknown but it may be a form of compartmental injury to the infraspinatus muscle. Over time, the damaged muscle is replaced by fibrous tissue and results in the characteristic physical and gait changes.
History
Lameness may occur in active dogs after a period of strenuous activity. Initially the lameness may resolve, followed by the characteristic gait and limb findings several weeks later.
Clinical Findings
Dogs with infraspinatus contracture hold their distal extremity in abduction, with the foot externally rotated and the elbow rotated toward the chest. Dogs tend to paddle the leg when they walk, "flipping" the carpus at the end of the swing phase of gait and they are unable to fully extend the scapulohumeral joint.
Diagnostics
Treatment Options
If identified very early, physical rehabilitation may possibly prevent further contracture. Surgical management is usually necessary and involves transecting the fibrous tissue and tendon to release the affected tissue. Postoperatively, the dog should be allowed full weight bearing as soon as possible, and given gentle, pain-free PROM exercises to the shoulder, elbow, and carpus several times daily to maintain ROM and to promote normal alignment of the healing tissues. Excessive activity should be avoided in the first several weeks to avoid tissue damage and recurrence of fibrous tissue. General conditioning exercises for the limb, should be used to gradually return muscles to normal size and strength.
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Characteristic posture of a dog with infraspinatus muscle contracture. Note the internal rotation of the elbow and external rotation of the lower limb.
Fracture
Signalment
Breeds – Any breed
Gender – No gender predilection
Age – Any age
Etiology – Trauma. Many cases occur as a result of automobile trauma. Because of this and the fact that the forelimb is affected, careful evaluation of the thoracic structures is important to detect cardiac arrhythmias, pneumothorax, pulmonary edema, or diaphragmatic hernia.
History
Often owners witness trauma, such as a fall, hit by automobile, or other sudden traumatic event that results in sudden onset of severe lameness.
Clinical Findings
Fractures of the shoulder joint result in pain on manipulation and crepitation.
Diagnostics
Radiographs are generally diagnostic, but CT evaluation may give additional details.
Treatment Options
Most fractures of the shoulder joint require internal fixation to restore joint anatomy and minimize arthritis development.